A U.S. spaceflight company is hoping the third time's the charm
in order to launch a brand-new rocket into space on its maiden
flight today (April 21).

After two delayed launched attempts, the privately built
Antares rocket is once again poised to blast off from a
seaside pad at NASA's Wallops Flight Facility on Virginia's
Eastern Shore. Liftoff is set for 5 p.m. EDT (2100 GMT).

Today's launch attempt will be the third in a week for Antares,
which was built by the Dulles, Va.-based Orbital Sciences Corp. A
minor mechanical glitch thwarted a launch try on Wednesday (April
17) just minutes before liftoff. Strong winds prevented and an
attempted launch on Saturday. [ LaunchPad
Photos: Antares Rocket Ready to Fly ]

The Antares rocket is designed to launch Orbital's unmanned
Cygnus spacecraft on cargo delivery missions to the International
Space Station for NASA. Orbital has a $1.9 billion contract to
provide at least eight cargo deliveries using Cygnus and Antares,
but first the company wants to make sure the rocket will perform
as expected.

"Obviously we would like to have gone Wednesday. But going
through the prelaunch procedures a couple of times now is great
experience for our launch team," Orbital spokesman Barron Beneski
told SPACE.com in an email. "Practice now will pay
dividends later when we are down to a small launch window, less
than five minutes, for our [space station] resupply missions
later this year."

Orbital
Sciences has a three-hour window for today's attempted
launch. The 13-story Antares rocket will lift off from the new
Launch Pad 0A at the Mid-Atlantic Regional Spaceport at the
southern tip of Wallops Island, Va., where it shares land with
NASA's Wallops Flight Facility is based. The NASA center has long
been the home of the agency's small sounding rocket launches and
balloon science projects.

"We have also been pleased with the performance of the vehicle
and the launch facility. We have not been working any technical
issues, which has been encouraging," Beneski said. "That's
remarkable since this is a first time launch for the rocket and
the pad."

Today's launch attempt will not carry a full Cygnus spacecraft
into orbit. Instead, the rocket is topped with a mockup that will
mimic the weight of an actual cargo ship. The rocket is also
carrying three coffee
cup-size Phonesat satellites — named Alexander, Graham
and Bell — as part of a space technology experiment for NASA. A
fourth nanosatellite, called Dove 1, is also being flown for a
commercial customer, Orbital officials said.

Orbital is one of two companies with NASA contracts to deliver
space station cargo. The Hawthorne, Calif.-based firm Space
Exploration Technologies (SpaceX) also has a $1.6 billion deal
for at least 12 cargo missions using its Falcon 9 rockets and
unmanned Dragon space capsules.

NASA's space shuttle fleet retired in 2011, so the space agency
is relying on Orbital Sciences and SpaceX to fly American cargo
to the International Space Station. NASA officials also hope to
launch American astronauts to the station using private
spaceships by 2017. Currently, the U.S. space agency relies on
Russia's Soyuz spacecraft to ferry crews to and from the station.

There is a chance that observers along much of the U.S.
East Coast could spot the Antares rocket soaring toward space
during today's launch test. NASA has advised local observers to
watch the launch from its Wallops Flight Facility Visitors Center
or the nearby Assateague National Seashore.
Maps and graphics released by Orbital officials,
however, suggest the launch could be seen from as far north as
Portland, Maine, and as far south as Charleston, S.C., weather
permitting.

Editor's note: If you snap a great photo of
Orbital's Antares rocket launch that you'd like to share for
a possible story or image gallery, send photos, comments and your
name and location to managing editor Tariq Malik at spacephotos@space.com.